1. Field of the Invention
The invention relates to a parking assist apparatus and a parking assist method for a vehicle for guiding the vehicle to a target parking position set by a user along a target path.
2. Description of the Related Art
JP-A-11-208420 discloses a parking assist apparatus that superimposes on a target parking frame adjustable by a user (the image of the vehicle that has been automatically parked) with an actual image of the view around the vehicle displayed on a display monitor. The art disclosed in this publication allows the user to set the target parking position of the vehicle such that the intention of the user is reflected, for example, to draw the vehicle to be close to the right side or left side of the parking frame. Unlike the apparatus having the system that automatically determines the target parking position based on the detection results of sensors or the image recognition results, the disclosed apparatus is capable of preventing the vehicle from being automatically guided to the parking target position against the intention of the user.
JP-A-10-264839 also discloses a parking assist system that automatically guides a vehicle to a target parking position. This parking assist system estimates a current vehicle position based on each wheel speed detected by the respective vehicle wheel speed sensors and a yaw rate detected by a yaw rate sensor. When it is determined that the current vehicle position deviates from the target path, each steering angle of the wheel is corrected in accordance with the amount of the deviation from the target path so as to correct the deviation.
In a generally employed parking assist apparatus as aforementioned, the current vehicle position monitored under the parking assist control is an estimated value based on such information as detection results of the vehicle wheel speed sensor, yaw rate sensor and the like. Assuming that there is a disturbance on the road surface or the abnormality in the system (failure in the yaw rate sensor, for example), the apparatus may recognize the current vehicle position as being on the target path, as it cannot detect the error that actually occurs between the estimated current vehicle position and the actual vehicle position. In this case, the parking assist control is continued until such error is detected. As a result, the vehicle is guided to the position different from the target parking position that has been originally set by the user.